This specification relates to a data communication system and, in particular, a system that implements real-time, scalable publish-subscribe messaging.
The publish-subscribe pattern (or “PubSub”) is a data communication messaging arrangement implemented by software systems where so-called publishers publish messages to topics and so-called subscribers receive the messages pertaining to particular topics to which they are subscribed. There can be one or more publishers per topic and publishers generally have no knowledge of what subscribers, if any, will receive the published messages. Because publishers may publish large volumes of messages, and subscribers may subscribe to many topics (or “channels”) the overall volume of messages directed to a particular channel and/or subscriber may be difficult to manage.